package invs.invs300both;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class InvsBase64 {
	   private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();  
	   
	    public static String encode(byte[] data) {  
	        int start = 0;  
	        int len = data.length;  
	        StringBuffer buf = new StringBuffer(data.length * 3 / 2);  
	  
	        int end = len - 3;  
	        int i = start;  
	        int n = 0;  
	  
	        while (i <= end) {  
	            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff);  
	  
	            buf.append(legalChars[(d >> 18) & 63]);  
	            buf.append(legalChars[(d >> 12) & 63]);  
	            buf.append(legalChars[(d >> 6) & 63]);  
	            buf.append(legalChars[d & 63]);  
	  
	            i += 3;  
	  
	            if (n++ >= 14) {  
	                n = 0;  
	                buf.append(" ");  
	            }  
	        }  
	  
	        if (i == start + len - 2) {  
	            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);  
	  
	            buf.append(legalChars[(d >> 18) & 63]);  
	            buf.append(legalChars[(d >> 12) & 63]);  
	            buf.append(legalChars[(d >> 6) & 63]);  
	            buf.append("=");  
	        } else if (i == start + len - 1) {  
	            int d = (((int) data[i]) & 0x0ff) << 16;  
	  
	            buf.append(legalChars[(d >> 18) & 63]);  
	            buf.append(legalChars[(d >> 12) & 63]);  
	            buf.append("==");  
	        }  
	  
	        return buf.toString();  
	    }  
	  
	    private static int decode(char c) {  
	        if (c >= 'A' && c <= 'Z')  
	            return ((int) c) - 65;  
	        else if (c >= 'a' && c <= 'z')  
	            return ((int) c) - 97 + 26;  
	        else if (c >= '0' && c <= '9')  
	            return ((int) c) - 48 + 26 + 26;  
	        else  
	            switch (c) {  
	            case '+':  
	                return 62;  
	            case '/':  
	                return 63;  
	            case '=':  
	                return 0;  
	            default:  
	                throw new RuntimeException("unexpected code: " + c);  
	            }  
	    }  
	  
	    /** 
	     * Decodes the given Base64 encoded String to a new byte array. The byte array holding the decoded data is returned. 
	     */  
	  
	    public static byte[] decode(String s) {  
	  
	        ByteArrayOutputStream bos = new ByteArrayOutputStream();  
	        try {  
	            decode(s, bos);  
	        } catch (IOException e) {  
	            throw new RuntimeException();  
	        }  
	        byte[] decodedBytes = bos.toByteArray();  
	        try {  
	            bos.close();  
	            bos = null;  
	        } catch (IOException ex) {  
	            System.err.println("Error while decoding BASE64: " + ex.toString());  
	        }  
	        return decodedBytes;  
	    }  
	  
	    private static void decode(String s, OutputStream os) throws IOException {  
	        int i = 0;  
	  
	        int len = s.length();  
	  
	        while (true) {  
	            while (i < len && s.charAt(i) <= ' ')  
	                i++;  
	  
	            if (i == len)  
	                break;  
	  
	            int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3)));  
	  
	            os.write((tri >> 16) & 255);  
	            if (s.charAt(i + 2) == '=')  
	                break;  
	            os.write((tri >> 8) & 255);  
	            if (s.charAt(i + 3) == '=')  
	                break;  
	            os.write(tri & 255);  
	  
	            i += 4;  
	        }  
	    }  

}
